The present invention relates to phased array antenna systems, and more particularly to a space-fed phased array antenna system specifically adapted for use on an exterior portion of a fuselage of an aircraft.
With the growing interest in providing live television programming and Internet connectivity with aircraft in flight, the design and implementation of phased array antenna systems has become extremely important. The Boeing Company is a leading innovator in the design and manufacture of phased array antennas systems. U.S. Pat. No. 5,886,671 to Riemer et al and U.S. Pat. No. 5,276,455 to Fitzsimmons et al both disclose packaging architectures for phased array antennas, and are each hereby incorporated by reference into the present application.
When implementing a phased array antenna on an aircraft, such as may be employed in the Connexion By BoeingSM system, an important consideration is that the antenna be able to scan close to the horizon when the aircraft is at high latitudes. This heretofore required a very large antenna aperture to be disposed on a top area of the fuselage of an aircraft. However, a very large aperture of a phased array antenna is quite expensive to manufacture. Accordingly, it would be highly desirable to provide some form of antenna system which is able to make use of an antenna having a smaller aperture but which still is able to project a beam close to the horizon when the aircraft is traveling at high latitudes.
The above and other drawbacks are overcome by a structurally-integrated, space-fed phased array antenna system. The antenna system of the present invention makes use of a conformal antenna aperture which is mounted on an exterior surface of a mobile platform. In one preferred embodiment the mobile platform comprises an aircraft. In this embodiment the conformal antenna aperture is mounted on one of the port or starboard sides of the fuselage of the aircraft along the rear one-half of the fuselage. More preferably, the conformal antenna aperture is mounted on one of the port or starboard sides of the fuselage closely adjacent to one of the horizontal stabilizers of the aircraft. That horizontal stabilizer includes an antenna, such as a feedhorn, which is structurally integrated therewith. In a preferred embodiment the feedhorn is integrally formed at a leading edge of the horizontal stabilizer such that it does not produce any additional aerodynamic drag on the aircraft when the aircraft is in flight. The feedhorn provides a space feed to illuminate the conformal antenna aperture disposed on the fuselage, which in turn is able to reflect the beam at an angle that allows the beam to be directed close to the horizon when the aircraft is traveling at high latitudes.
In another preferred embodiment the conformal antenna aperture is divided into two antenna apertures: a receive antenna aperture and a transmit antenna aperture. In other preferred embodiments the feedhorn is also presented as two independent feedhorns mounted closely adjacent one another on a leading edge of a horizontal stabilizer of the aircraft.
The above described preferred embodiments all enable a conformal phased array antenna system used on an aircraft to readily project a beam below the horizon when the aircraft is flying at high latitudes. Moreover, the antenna system of the present invention does not add significantly to the aerodynamic drag experienced by the aircraft during flight.
The present invention is equally applicable to any mobile platform such as a land vehicle, ship or satellite. A principal advantage of the present invention is that the use of a space feed allows a much larger antenna aperture to be illuminated.
Further areas of applicability of the present invention will become apparent from the detailed description provided hereinafter. It should be understood that the detailed description and specific examples, while indicating the preferred embodiment of the invention, are intended for purposes of illustration only and are not intended to limit the scope of the invention.